PLEASE MAKE ANSWER CLEAR, I\'LL RATE AS SOON AS I CAN, THANKS! A child is sittin
ID: 2289479 • Letter: P
Question
PLEASE MAKE ANSWER CLEAR, I'LL RATE AS SOON AS I CAN, THANKS!
A child is sitting on a stationary skateboard with a pile of rocks which she throws in one direction in order to make the skateboard travel in the opposite direction. If the rocks each have a mass of 0.40 kg and she can throw them with a speed of 20 m/s relative to the ground, determine the number of rocks she must throw per minute in order to maintain a constant average speed against a 2.9 N force of friction. (Note: because this is a rate, the answer may not be a whole number.)
1 rocks/min
Explanation / Answer
let m be the mass she is throwing per second
mv = F
m =F/v = 2.9/20 =0.145 kg
total mass thrown in one minute = 60m = 8.7 kg
number of stones = 8.7/0.4=21.8
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